I'm organising my friend's hens night for this Saturday & am worried I don't have enough drinks. I am providing soft drink & they are providing their own alcohol if they want. There are 18 women. Two are pregnant so won't be drinking alcohol & four others won't drink either, or will have very little because they are driving home. We are starting at 1pm with pampering treatments & then going all night as a big pyjama party. I have 13L of soft drink and am thinking it might not be enough. Should I be catering for at least a litre per person? What would you allocate?